Method and apparatus for making hollow rubber articles



March 8, 1949.

Filed July 10, 1945 F. T. ROBERTS ET AL METHOD AND APPARATUS FOR MAKINGHOLLOW RUBBER ARTICLES 3 Sheets-Sheet 1 FIG. 2

JNVENTORS.

JF' @wJ r March 8, 1949. F. T. ROBERTS ETAL 2,453,562

METHOD AND APPARATUS FOR MAKING HQLLQW RUBBER ARTICLES Filed July 10,1945 3 Sheets-Sheet 2 25 2o v. ;:I" IIIIIII [N V EN TORS- March 8,.1949.F. T. ROB TS ETAL 2,463,562

MET D AND APP AT FOR MAKING OLLOW RUBBER TICLES Filed July 10, 1945 3Sheets-Sheet S Patented Mar. 8, 1949 METHOD AND APPARATUS FOR MAKINGHOLLOW RUBBER ARTICLES Fred Thomas Roberts and Robert Eldon Roberts,Ridgefleld, Conn.

Application July 10, 1945, Serial No. 604,204

21 Claims.

The object of this invention is to provide a method of forming balls andsimilar articles out of sheet rubber and effectively joining the seamsthereof and to provide a simple apparatus which may be employed incarrying out such method. Briefly, in our method, we take a flat sheetof rubber vor similar material and buckle it inwardly in areas radiatingfrom a center and bring together the material at opposite edges of suchinwardly diverted portions to form'seams whereby the flat disc ofmaterial is converted into a cup-shaped member with seams extending inmeridional directions, and it is a further object of this invention toprovide for the ready deflection of the material in the regions to bediscarded and for. bringing the remaining material together at the edgesof such diverted portions to form the seams.

Our apparatus is shown in the accompanying drawings, and serves toillustrate also the method employed, and the description of the showingof such drawings further explains both the method and apparatus.

In the drawings, Fig. 1' is a plan of the apparatus, in position toreceive a flat disc of rubber to be formed into cup-shape; Fig. 2 is aplan of a portion of such apparatus in its final position, which itoccupies when the flat sheet has been converted into a cup; Fig. 3 is avertical section v through the apparatus in sheet-receiving condition,this view showing the sheet resting by gravity on top of the apparatus,the plane of the sections being indicated by the line 33 on Fig. 1; Fig.4 is a sectional side elevation of the apparatus in its final form, thesection being in the plane indicated by the line 4-4 in Fig. 2; Fig. 5is a detail in section through two adjacent supporting members of theforming apparatus after they have come together and pinched oi! theinwardly diverted portion of the rubber sheet, the location of thissection being indicated for instance by the line 5---! on Fig. 4; Fig.5a is a view similar to a portion of Fig. 5, showing a reinforcing stripcovering the seam; Fig. 5B is a fragmentary sectional perspective of aV- shaped piece which may be inserted at the junction of the two articlehalves; Fig. 6 is a side elevation of an article as formed by theapparatus of Figs. 1 to 5; Fig. 7 is a vertical section through atwo-part forming mold in which two of the articles of Fig. 6 are mountedand brought together to form a ball; Fig. 7a is a vertical sectioncorresponding to part of Fig. 7, showing a valve plug on the interior ofthe article; Fig. 1B is a plan of a mold member having a number ofcavities and passages, as shown individually in Fig. '7; Fig. 8 is aview of such completed ball.

Referring first to Figs. 1 to 5, Ill indicates a supporting standardwhich may be a vertical rod mounted on a suitable base not shown. At itsupper end this rod carries several projecting wings l2 which are hingedto the rod. As shown the rod has a square head II, formed along its foursides with hinge ears l2, and we have shown four wings or "petals 20,the inner edges of which are curled into hinge ears 2!, suitable pintles22 connecting the petals to the head of the standard. These petals areso formed that they are concavo-convex in both radial and transversedirections, and for making a spherical article they are for the mostpart sections of a sphere, so

that when lowered into cup shape their edges abut along meridionallines.

The apparatus shown in the drawings has four radiating petals and whenthat number is employed, and the apparatus is to form a hemisphere, eachpetal will comprise about a fourth of a hemisphere. Whatever the numberof petals, or whatever shape of article is to 'be produced, the edges ofthe petals are so formed that when the petals swing down from theextended approximately horizontal position, indicated in Fig. 3, toclosed position of Fig. 4, the edges of adjacent petals contact witheach other and thus serve to pinch off any material depending into thespaces between them and f orm a seam in such material.

Preferably each of the petals is formed with an arcuate lip 24 at itslower edge beyond the spherical portion of the petal to produce anexternal annular rim on the cup-shaped article formed. This rim is ofuse in joining one cupshaped article to another to make a complete ball,as hereinafter explained.

Slidably mounted on the standard It is a slide 30 connected by links 3|with the interior .of the respective petals. As shown there are four ofthese links each pivoted to the upper end of the slide apart and eachpivoted at its outer end to an ear 25 on the inner faceof the petal.When the slide 30 is in its elevated position, as shown in Fig. 3, thepetals are all spread into substantially horizontal position ready toreceive the sheet of material to be formed- In operation, a suitabledisc of material is laid on such extended petals and being thin andflexible conforms to the upper surface thereof, as shown in the case ofthesheet A in Fig. 3. Where such sheet bridges across'the space betweenthe petals it tends to sag by gravity into such space.

3 However, to insure it remaining in the space as the petals arelowered, we provide a series of radial bars 40 which are adapted tooverlie the sheet of material and pull it down into the space betweenthe petals.

As shown, the four bars 40 extend inward radially tolformafringll.andare then bent upwardly approximately-as shown at 42. We have shown asupport for the ring 4| comprising a second ring 45 connected by radialarms 46 to the main slide 30 and having an outwardly extendinghorizontal flange. The bar supporting ring 4| is shown as resting on theoperating ring 45 and as latched thereto by latches 48 pressed inwardlyby suitable springs 49.

In operation after the disc of material has been placed on the spreadpetals the ring 4| is mounted on the frame 45, thus causing the bars 40to press the material downwardly in the region between the petals. Nowas the slide 30 is lowered the petals are swung downwardly and the edgesapproach each other and at the same time the bars 40 carriedby the ringsare moved downwardly so that the bars always keep ahead of the closingpetals and in the final position the petals have sheared off the excessof rubber and formed meridional seams of a complete hemisphere, the barsholding the excess inwardly of such hemisphere, as shown in Fig. 4. Asshown in Fig. 5, the petal edges are chamfered, so that they spread fromthe concave side, and thus force together the material across the edges,making an effective seam.

The apparatus and operation above described produces the article of Fig.6 comprising the hemisphere B with a projecting rim C. Two of thesehemispheres are now brought together with their rims abutting eachother, and the rims are pressed together to form an equatorial seam andare then sheared off to make a complete article.

Fig. 7 illustrates suitable apparatus for forming such junction of thetwo hemispheres. As shown, this apparatus comprises a pair of moldmembers 50 each having a cavity in which the article B may seat. Eachmold member is provided with a passageway 5| communicating at 52 withthe article cavity and connected to a conduit 53 by which the cavity maybe exhausted of air. Preferably also the mold has an annular groove 55surrounding the cavity and connected with the passageway 5| bypassageways 56.

,When the article of Fig. 6 is placed in the cavity of one of the moldmembers 50 and the air exhausted from the cavity beneath the articlethrough the exhaust pipe 53, the rim C of the article is clamped by thesuction to the groove 55 and the body of the article B is drawn down bysuction against the wall of. the cavity.

When the articles have been thus seated in 'two mold members 50, suchmembers are brought together' under pressure and the cutting edges 58 ofthe mold members between the main cavities and the surrounding grooves55 pinch oil the excess of the rubber rim C and :by their inclinedannular surfaces form an effective equatorial seam. After the separationof the mold members and the removal .of the article, the exterior of theequatorial seam is 'bufi'ed off, resulting in the formedarticle readyfor vulcanizingin the presej'nt'rcase the'sphereD of Fig. 8.vulcanization may beefiectedby heat in a separate mold, or

the mold of, Fig. 7 may be employed with means to plug. the exhausting,openings .52 and an annularj reinforce surrounding the cutting edges,or, if

I desired, acid-curing may be used.

While we have shown a sphere as illustrative of the article to beproduced by our method and apparatus, it is to be understood that thesame operation, with an apparatus of correspondingly diflerent shape,may be employed for articles of other form, as for instance a spheroidsuitable for a football bladder.

In the manufacture of football bladders and similar articles to beexternally inflated, it is desirable to provide a self-closing valveplug on the interior of the article, such plug being adapted to have ahypodermic needle passed through it for inflation purposes, the plugsealing the opening when the needle is withdrawn. Such a plug is shownat E in Fig. 7a, the plug having a skirt e cemented to the interior ofthe rubber ball. When such a plug is to be employed we make a recess.indicated at Ila in the head H of the apparatus however, that the twomold members 50 may each have a number of cavities so that several ofthe cup-shaped members maybe formed at the same time. Such aconstruction is illustrated in Fig. 73 where 50a indicates a mold platecorresponding to the member 50 of Fig. 7, but having a number ofcavities, the construction otherwise bearing the same reference numeralsof Fig. 7.

It has been found that the present synthetic rubber is not as tacky, orself-adhering, as the regular natural rubber, and in most cases where 40seams of this kind are made, when the synthetic rubber compound is used,it is desirable to strip or reinforce such seams with a thin piece ofrub.

ber of the same synthetic rubber compound as used to make the article.Such strips of rubber may be a very thin piece of calendered rubber or avery small V-shaped piece, run on a tubing machine, which is presseddown into the V shown at the junction of the two pieces of rubber at thescam in Fig. 5. Such reinforcing strip is shown in cross section at A inFig. 5a and the V-shaped strip is shown in cross section at A2 in Fig.53. It is either cemented or cleaned with naptha and as it is on theoutside of the ball and against the mold when cured it has been foundthat it does not show at all after the ball is finished and adds verylittle thickness to the same but does give strength.

The seam made from joining the two halves together is also strippedonthe outside, the strip in this case being put over the equatorial V ofthe seam. As the compounding of the synthetic rubber progresses, it maymore clearly resemble the natural rubber and be more easily seamed andthen it may not be necessary or desirable to strip these seams, as theyare all formed by chamfered edges of metal which are pressed together byhydraulic pressure.

It will be seen that our method and apparatus are comparatively simple.When the wings of the apparatus are extended it is merely necessary tolay a sheet of raw rubber or similar material on the apparatus, suchsheet by gravity naturally sagging between the wings, and then to putthe member carrying the bars in place with the bars extending over thesagging regions of the rubber 2,4os,sea

and then tolower the slide. This results in the unsupported portion ofthe material bein brought inwardly in radial puckers until the supportedportions are joined by meridional seams into a cup-shape, the retainingbars moving downwardly ahead of the material and being thus on theinterior of the cup produced.

The provision of an annular skirt on the cupshaped member producedenables two such cup- 1. The method of making cup-shaped members ofplastic material having adhesive characteristics comprising supportingan approximately flat area of such material and causing substantiallyradial regions thereof to be diverted in- -wardly out of the generallocus of the material and pinching the material together at the edges ofthe diverted regions to form seams.

2. The method of making a cup-shaped article of rubber or similarmaterial from a substantially flat disc thereof comprising causing suchdisc to be diverted inwardly in substantially radial directions'whilethe disc is on a support having sep arated supporting members and thengradually moving said members until the edges thereof coact to shear ofland join material which has been diverted.

3. The method of making cup-shaped articles comprising taking a sheet ofrubber or similar material, supporting such sheet by movable membersextending substantially radially from a cen. terwith radial flaringspaces between them, allowing the sheet to sag between the supportingmembers, lowering the supporting members with the sheet resting thereonby gravity and its own adhesion to cause the material depending betweenthe members to become loops within the cup-shaped article which abutthemselves adja cent the material on the supporting members, andpressing and shearing of! such material at the loops.

4. The method of making cup-shaped members of sheet material similar torubber comprising supporting a sheet of such material on a supporthaving radiating separated members so that the sheet may sag between themembers. gradually swinging the members downwardly substantially about acenter and at the same time pressing the sagging material between themdownwardly and inwardly and bringing the supporting edges toward eachother to shear oi! the said sagging material and form meridional seamsthereat to form a cup-shaped member.

5. The method of making hollow articles comprising taking two sheets ofrubber or similar material, placing each across a support having spacedmembers extending radially from a central region. whereby the rubbersheet may sag between the members, lowering said members to shear oi!the sagging portions and join the adjacent edges to make a cup-shapedmember with a projecting rim, and thereafter placing two of such memberstogether to form a junction at the projecting rims.

6. An apparatus for making cup-shaped articles of plastic sheet materialcomprising pivotally mounted convex wings adapted to carry a sheet ofplastic material on their convex surfaces with 6 thesheet divertedbetween the wings, mechanism for swinging said wings to form the plasticmaterial into cup-shape, the wings being so shaped thatthe edges oiadjacent wings operate to form a seam.

'I. An apparatus for making cup-shaped articles of plastic sheetmaterial comprising an upright standard, radiating upwardly convex wingspivoted thereto and adapted to support a sheet of plastic materialresting on the wings with the sheet sagging between the wings, mechanismfor swinging said wings downwardly to form the plastic material intocup-shape external 01 the wings. the wings being so shaped that theedges or adjacent wings cooperate to form a meridional seam and pinchoff the sag i material.

8. The combination of a suitable support, a series of radial wingspivotally carried thereby and eachcomprising a section of a sphere withits convex surface outward, means for supporting said wings extendedwhereby they may support a sheet of raw material resting thereon, andmeans for swinging said wings inwardly to form a junc-- tion of thematerial sagging between the wings.

9. In an apparatus for making cup-shaped articles of plastic material,the combination of the standard, a series of radial wings hinged theretoslide to the wings whereby they may be extended to form a support for anapproximately flat sheet of material or be swung toward each other tocause their exterior to assume the cup-shaped form, the wings being soshaped that their edges come into abutting relation when they are swunginto the cup-shape whereby the supported material may be joined to makea cup-shaped article.

10. The combination of a standard, a series of wings hinged theretoadapted to extend therefrom in different radial directions to formpetals adapted to support a sheet of plastic material, mechanism forswinging the wings inwardly, and means for pressing inwardly thematerial between the wings as the edges of the wings approach eachother, said edges being formed to coact and pinch the material betweenthem.

11. An apparatus for making cup-shaped articles of sheet plasticmaterial comprising a central standard, wings hinged tothe top of thestandard and extending radially outward therefrom, the wings being soshaped that their edges may come together .as the wings are swungdownwardly toward the central standard, means for so swinging the wingsand means for drawing inwardly the material between the wings as theedges of the wings approach each other.

12. The combination of a central standard, a set of wings hinged to thetop of the standard and extending outwardly therefrom in radial di-'-rections, means for swinging the wings inwardly along their pivots, asetof bars adapted to be placed over the material between the wings andmeans for lowering said bars as the wings are brought together.

13. An apparatus for making cup-shaped articles from sheet materialcomprising a standard, radial wings hinged to the top of the standard,each wing being arcuate in the radial direction and also transverselythereof, a slide on the standard, links connecting the slide with thewings, an annular support carried by the slide, a series of inwardlyprojecting bars carried by the annular support and adapted to overliethe material depending between the wings.

14. The method of making a hollow elastic ball comprising seatin'g sheetstock on the exterior of a convex forming member having an outwardannular flange, such stock extending across the flange, thereafterbringing two of the formed sections together with the flange portionsabutting and joining the same under pressure.

15. The method of making cup-shaped articles of plastic sheet materialcomprising placing such material about the exterior of a forming member,causing loops of the material to pass through spaces in the formingmember, removing such internal material and pinching together theadjacent edges of the remaining material to form a seam.

16. The method of making a rubber article having panels joined bymeridional seams, comprising placing sheet rubber on the exterior of aforming member, causing loops of such material to pass into the interiorof the forming member through meridional slots therein, removing theexcess of such material from the interior of the forming member, andpinching together the ad jacent edges of the panels to form meridionalseams.

17. An apparatus for forming cup-shaped rubber articles comprising aforming member composed of spaced movable panels on the exterior ofwhich a rubber sheet may be mounted, means for diverting the sheetthrough meridional spaces between the panels, and means for bringing thepanels into edge coaction to pinch oif the internally projectingmaterial and at the same time form meridional seams between thedifferent panels of the remaining material.

18. In the method of making hollow articles of plastic sheet material,the steps comprising taking sheets of such material, bending the sameand looping regions thereof out of the general locus of the material andpinching such loops together to form seams, thereby producing cupshapedmembers, while leaving outwardly projecting flanges at the annular edgesof such members, whereby a single hollow enclosing member may be made byabutting and joining the flanges of two of such cup-shaped members.

19. The combination 01 a standard. a set of radial wings hinged to thestandard adjacent the top thereof, each wing being curved in a radialdirection and also transversely, each wing formed with a flaring portionadjacent its outer edge, means for swinging the wings inwardly on theirpivots, whereby a sheet of material resting on the wings and sag ngbetween them may be converted into a cup-shaped member having aprojecting rim. 1

20. An apparatus for making cup-shaped members comprising a standard, aset of radial wings hinged to the standard adjacent its top and adaptedto extend outwardly like petals, each wing being substantially a sectionof a sphere with a flaring portion at the extreme end, a ring carryinginwardly projecting radial rods, means for supporting the ring and meansfor swinging the wings inwardly and for lowering the rods to maintainthem on the interior of the wings.

21. An apparatus for making cup-shaped ar- REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 637,372 Cox Nov. 21, 18991,139,341 Cigol May 11, 1915 1,467,438 Lawton Sept. 11, 1923 2,370,827Weichbrodt et a1. Mar. 6, 1945

